Photovoltaic Cells: Energy Source of the Future.

Our supply of petroleum and gas is limited, but the photovoltaic cell offers a solution to the problem of a future energy shortage.. This cell is already an important source of energy..

Photovoltaic Cells:

As populations increase and countries industrialize, the world’s demand for energy increases Our supply of petroleum and gas is limited, but the photovoltaic cell offers a solution to the problem of a future energy shortage This cell is already an important source of energy In fact, it seems almost like magic The photovoltaic cell changes sunlight directly into energy Solar energy – energy from the sun – is clean, easily available, inexhaustible, and free, if the equipment is available

Did you ever reach to open the door at a stories or hotel and see it open by itself? Does your camera always let in the right amount of light for your picture? These are examples of uses of photovoltaic cells They are also used in calculators and watches, in remote telecommunication units, and in central power stations to produce electricity Another important use is in the space exploration program This program could not exist without the energy produced by photovoltaic cells

The photovoltaic cell is simple It has transparent metallic film at the top Below this is a layer of silicon A metal base is at the bottom

The sunlight falls on the boundary between the two different types of semiconductors in the photovoltaic cell, the silicon and the metal base A conductor is the something that electricity can pass through Water and metal conduct electricity, but wood does not A semiconductor conducts electricity poorly at low temperatures, but when heat or light is added, conductivity is increased

As the light falls on this boundary between the two types of semiconductors, it creates an electric current The sunlight is converted directly into electricity

One advantage of the photovoltaic cell is that it is solid-state; that is, there are no moving parts Since there are no moving parts to break down, the cell will last the long time if it is protected from damage This protection

is important If the top of the cell get dusty, less light enters, and the cell doesn’t work as efficiently as it should

In addition, silicon is one of the most common elements in the world; for example, sand is made up mostly of silicon At one time, the chemical preparation of silicon for used a photovoltaic cell was very

expensive Now the cost has gone down a great deal Scientists have also found a way to produce silicon in long sheets, similar to the way plastic for plastic bags is made today This is helping the cost of a units of solar energy

to fall even more Today, there are large factories using solar- cell systems in

a number of countries

About 18% of the sunlight that reaches the photovoltaic cell is converted into electricity This is a small amount, so many cells must be used to create a reasonable amount of electricity However, technology can

be developed to make the cells more efficient and raise the percentage of sunlight converted to 27%

What does solar energy mean to the world? Photovoltaic cells have several advantages over fossil fuel (gas, oil, and coal) Fossil fuels that we use today were formed from plants and animals that lived millions of years ago Those plants and animals were able to exist because of the sun Obviously, we can’t wait million years for more fossil fuels The photovoltaic cell gives us ability to produce energy directly from the sun The sun’s energy can be converted for use immediately

At the present time, gas and oil are expensive Developing countries can not export enough agricultural products and other raw materials to allow them to import the fuel that they need to produce energy At the same time, petroleum supplies are limited, and in a few decades, they will run out However, the supply of sunlight is limitless, and most of the poor countries

of the world are in the tropics, where there is plenty of sunlight

The photovoltaic cell has another very important advantage It is a clean source of energy The fossil fuels that we use today are the main source of the pollution in our atmosphere

Although many individuals and government have been reluctant to reduce their dependence on fossil fuels, there is a growing market for solar energy on satellites and then beaming it to Earth This process is called Space Solar Power If we truly want cheaper and better ways to create energy, solar power offers many possibilities

Biosphere in Space.

Will it ever for possible for people to live on faraway planets such as Mars? In the past, colonies in space were possible only in science fiction stories Today, however, we are experimenting with ways to build real space colonies Many scientists actually consider it possible that people will live far from the Earth in the future

The Environment Research Laboratory at the University of Arizona is one place that designs biosphere (bio mean life, and a sphere is a circle, like a ball) which could use to live on other planets Biospheres are complete, enclosed environment where people can be born, live their whole live, and die without returning to the Earth To be successful, a biosphere has to have perfect balance among everything within it- the planets, the animals (including humans), and the chemical elements Specialist and experts from many different fields are needed to work on these complex projects

Building a greenhouse for growing planets in winter is the first step in creating a biosphere A greenhouse is a closed environment except for the sun’s heat entering through the glass or plastic Of course, there is water system from outside, and people bring in nutrients for the planets and take out the waste material A biosphere in space will have to have its own system to provide water that can be used and reused It will need bacteria or something else to take care of the wastes Everything must be perfect balanced, or else the whole system will break down

The Earth itself is the best example of a real biosphere Nothing important enters except sunlight, and nothing leaves as waste except some heat Everything in the Earth’s environment needs to be in balance If we destroy that balance, the system will break down

There are several reasons for building biospheres One reason is to help out when there is an energy shortage Dr Gerard K O’Neill, a famous physicist from Princeton University, has said that in the future we will have satellites

in space to produce solar energy and send it to the Earth It will be too expensive to continually send people and materials to the satellites, so biosphere will be necessary He thinks that 10,000 people could live in the space colony sometime in the future There is another interesting reason to build biosphere We can use them to do all kinds of research about our own environment and how it works By studying biosphere, we can understand better what will happen as humans destroy tropical forests, as they create

more carbon dioxide by burning fuel, and as they pollute the ocean and the air

So far, only a few experimental biospheres have been built on Earth One is in Oracle, Arizona, near the University of Arizona In 1991, four men and four women tried to live inside the biosphere without getting anything from outside During the experiment, things got out of balance Oxygen and carbon dioxide levels fell, and the crew had to get help and supplies from outside In space, people living in a biosphere could not be able to do this

Learning how a biosphere works is one of the most important things

we can do The information we get from biosphere may keep us from destroying our own environment This information will also help us to travel where once only science fiction could go